Is wood a sustainable fuel? At first glance, it must be. Wood has been used as fuel for comfort and cooking for untold thousands of years. The so-called discovery of fire was the first revolution in human evolution. In addition, wood is a renewable resource. There are forests all around, and trees grow all the time. Wait a minute, though. Forests have been dwindling for quite a while. The agricultural revolution was the first blow for the forests, but the industrial revolution was much worse in this regard. Besides, the human population has been growing at a clip, and especially in the last few hundred years. If everyone turned to wood as fuel, forests would disappear in a short while. On top of that, the sky would turn dark and foul with all the smoke. So, wood is not a sustainable fuel at this point in human evolution. Which only adds to the joy of the fireplace. Staring into the leaping fire, one can feel the end of an era approaching. And fast. For it is either the forests or the humans that will dwindle into insignificance any time soon. As to all the other fuels, the story must be rather similar. If the human population keeps growing, no fuel will be sustainable for long.